Pandora Media, the online radio service with 27 million registered users, closed a round of financing and named David Sze of venture capital firm Greylock Partners to its board.

Sze led the investment round, Oakland-based Pandora said in an e-mailed statement. The amount and valuation weren’t disclosed. The new funds will be used “toward the continued growth and development of Pandora,” the closely held company said.

Pandora is adding 50,000 to 60,000 members a day and aims to double revenue this year to about $40 million, founder Tim Westergren said in May. Last week, the company resolved a two-year struggle over how much online radio sites must pay in music royalties, eliminating uncertainty about its viability that may have deterred some investors, an analyst said.

“What was killing Internet radio was it didn’t know what royalties it would have to pay,” Sanford C. Bernstein Internet analyst Jeffrey Lindsay said last month. “People just couldn’t take the risk.”

Pandora, which derives most of its revenue from advertising, aims to turn its first profit next year, Westergren said in May.